Unequal

from Simon Tatham's Portable Puzzle Collection

Fill in the grid with numbers from 1 to the grid size, so that every
number appears exactly once in each row and column, and so that all
the < signs represent true inequalities (i.e. the
number at the pointed end is smaller than the number at the open end).

To place a number, click in a square to select it, then type the
number on the keyboard. To erase a number, click to select a square
and then press Backspace.

Right-click in a square and then type a number to add or remove the
number as a pencil mark, indicating numbers that you think
might go in that square.